def f(n):
    if n <= 1:
        return 1
    else:
        return n*f(n-1)


num =int(input('请输入一个正整数：'))
s = f(num)
print(num,'的阶乘是：',s)


def sum(n):
    if n == 1:
        return 1
    else:
         return n+sum(n-1)
print('1~100相加的和为',sum(100))


def fibo(n):
    if n <= 2:
        return 1
    else:
        return fibo(n - 1) + fibo(n - 2)


print('斐波那契数列的第{}项为{}'.format(7,fibo(7)))


sum = lambda a,b,c: a+b+c
print(sum(1,2,3))

fun = lambda m: m**2
print(fun(5))